Gears for crimping yarn

ABSTRACT

Gears for crimping and in particular for crimping yarn in which at least one of the gears is an integral stepped structure having gear teeth on a portion of greater diameter and gear teeth on a portion of lesser diameter both sets of which teeth intermesh with teeth on another gear.

Unite States Fatet Dunnell et al.

[54] GEARS FOR CRIMPING YARN ['72] Inventors: Alan Keith Dunnell; David Greenwood; Thomas C. J. Wade, all of Pontypool, England [73] Assignee: Imperial Chemical Industries Limited, London, England [22] Filed: Nov. 13, 1970 [21] Appl. No.: 89,511

Related 0.8. Application Data [63] Continuation of Ser. No. 794,929, Jan. 29,

1969, abandoned.

[52] US. Cl. ..28/1.8 [51] Int. Cl. ..D02g l/14 [58] Field of Search ..28/1.8, 72.15; 74/457, 460

[451 Aug. 29, 1972 [56] References Cited UNITED STATES PATENTS 3,024,517 3/ 1962 Bromley et al. ..28/72.15 3,137,911 6/1964 Bromley ..28/1 .8 3,140,525 7/1964 Lamb ..28/1.8 3,204,319 9/1965 Baer et al. ..28/1.8 3,217,376 11/1965 Irwin etal ..28/1.8

Primary Examiner-Louis K. Rimrodt Attarney-Cushman, Darby & Cushman [5 7] ABSTRACT Gears for crimping and in particular for crimping yarn in which at least one of the gears is an integral stepped structure having gear teeth on a portion of greater diameter and gear teeth on a portion of lesser diameter both sets of which teeth intermesh with teeth on another gear.

'2 Claims, 3 Drawing figures GEARS FOR CRIIVEING YARN This application is a continuation of copending application Ser. No. 794,929, filed Jan. 29, 1969, now abandoned.

The invention concerns improvements in or relating to gears for crimping and in particular gears for crimping yarn.

Gear-crimping of yarn, for example, synthetic polymeric yarns such as those derivable from polyacrylics, polyamides, polyesters, polyolefins and the like and glass is accomplished by the simple process of passing the yarn through the meshing zone of two or more gears, at least one of which is positively driven.

A sinusoidal crimp is imparted to the yarn, or to a single filament if such constitutes the yarn, the frequency of which is dependent on the spacing of the gear teeth, and the amplitude of which is dependent on the extent of intermeshing of the teeth.

The present common practice is for the driving gear to impart rotary motion to the driven gear through the yarn. If there are any sharp edges on the gear teeth, this can result in filamentation or even the breaking of individual filaments of the yarn owing to the pinching action of driving teeth on driven teeth.

Some amelioration of this fault can be obtained by making at least one of the gears of a synthetic plastics material, as, for instance, Delrin (Registered trademark) polyoxymethylene material.

Nevertheless, this arrangement is not entirely satisfactory from other points of view, namely that the plastic gear, which will be the idler, is more liable to grooving by any yarn wraps, and to wear generally, than, for instance, a steel gear.

This invention is, therefore, concerned with the amelioration of the problem of yarn filamentation in a manner which is not detrimental to the wear life of the gears.

The invention consists in crimping gears comprising are both or all made of metal, when problems due to two gears in meshing engagement for the imparting of rotary motion by one or more of said gears which is driven and for the imposing of crimp to a material running therebetween in which at least one of said gears is an integral stepped structure having gear teeth on a portion of greater diameter and gear teeth on a portion of lesser diameter both sets of which teeth intermesh with teeth on the other gear.

The invention also provides a process for crimping a yarn which comprises passing the yarn between two or more gears in meshing engagement for the imparting of rotary motion by one or more of said gears which is driven and for the imposing of crimp to the yarn running therebetween in which at least one of the said gears is an integral stepped structure having gear teeth on a portion of greater diameter and gear teeth on a portion of lesser diameter both sets of which teeth intermesh with teeth on the other gear.

Preferably, the teeth of both or all the gears are involute in shape, in order that, over the working range of the gears operative to grip the yarn during the full period of intermeshing, a substantially constant gap between the sides of the teeth, where the yarn is gripped, is maintained.

By these means, it is possible to ensure that the yarn is never pinched by the meshing teeth, so that filamentation is at least substantially reduced even if the gears the wear of the gears will be minimized.

It will be appreciated that the full driving force is transmitted from the driving gear to the driven gear or gears entirely by the teeth around the periphery of the portion of greater diameter of the gear, or gears having a stepped construction, so that there is no actual contact between the sides of the teeth in the crimping portion of lesser diameter.

In fact, the magnitude of the step between the two portions of the stepped gear or gears is calculated to allow for a minimum gap between the sides of the teeth in the crimping portion, so that the particular diameter of yarn to be crimped may be accommodated without being pinched, whilst the yarn is still able to be gripped satisfactorily on its passage through the gears.

It is pointed out that stepped gears according to the invention, being of integral structure, are a great improvement over known gear systems in which driving pairs of gears and crimping pairs of gears are respectively mounted on two shafts. Not only are integral gears more simply and cheaply manufactured, but there is no need, as in the separated gears system, to cut the gears separately and then to assemble them on their respective shafts with extreme accuracy relative to one another, bearing in mind that the gap between the driving and crimping teeth flanks is of the order of only one to two thousandths of an inch.

According to a further embodiment of the invention, a pair of crimping gears comprises a straight spur gear and a stepped gear in meshing engagement. For a 40 denier/13 filament synthetic polymeric yarn the difference between the portion of greater diameter of the stepped gear and the portion of lesser diameter at the pitch circle diameter and the outer diameter is 0.009 inch.

Both gears may be made of stainless steel or even a synthetic plastic material; or alternatively the driving gear of stepped construction is of stainless steel, and the driven gear is of a synthetic plastic such as Delrin polyoxymethylene material.

The teeth around the periphery of the gears may be regular in size and spacing, or, if novelty efl'ects are required, the spacing may be irregular (the gears being matched in this respect) or the amplitude of the teeth may be varied around the gears.

Normally, however, regular spacing and amplitude of the teeth is desirable, but some de-phasing of the crimp is usually subsequently required and this may be brought about by subjecting the yarn to agitation by air turbulence before it is wound up. Some degree of outof-phase in the crimp may be attained if the teeth are helically arranged around the periphery of the gear wheel, rather than with their tips parallel to the axis thereof. Preferably, with any shaped teeth, the tips are rounded.

IN THE DRAWINGS FIG. 1 is a schematic front elevational view of a stepped gear intermeshing with a straight spur gear;

FIG. 2 is a detailed sectional view taken on the line 22 of FIG. 1; and

FIG. 3 is a schematic front elevational view of two intermeshing stepped gears.

Referring to FiGS. l and 2, there is shown a straight spur driving gear and a stepped gear 12 which is an idler gear. The stepped gear 12 has crimping teeth 14 on a circumference of relatively small diameter and driving teeth 16 on a circumference of larger diameter. The driving teeth 16 mesh with and engage teeth 18 on the driving gear 10. The crimping teeth 14 mesh with but do not engage the teeth 18, there being a gap 20 between the teeth 14 and the teeth 18 within which lies the yarn 22 being crimped. As shown, the yarn 22 passes alternately over the tips of the teeth 18 and 14.

In FIG. 3 the gear assembly includes two stepped gears 12 each of which is constructed in the shape of the gear 12 illustrated in FIG. 2. In this embodiment the teeth 16' intermesh and engage and the teeth 14' intermesh but do not engage. The yarn 22' passes first over the tip of a tooth 14 on one of the gears and then over the tip of a tooth 14' on the other gear.

The following example illustrates but does not limit the present invention.

A 40 denier, l3 filament yarn derived from polyhexamethylene adipamide was fed at 3,300 ftjmin. to a pair of stainless steel crimping gears comprising a straight spur gear and a stepped gear in meshing arrangement. The post gear yarn tension varied between 8 and 12 grams.

The dimensions of the two gears were as follows:

Overall width. H116" l l/lb" Width of driving portion. 3/16" 3H6" Width of crimping portion. 3/8 3/8" Number of teeth 363 363 Diametral pitch 120 I20 Step 0.0045" In 60 hours of running no filarnentation or breaks in the yarn or wear in the gears was observed and satisfactorily crirnped yarn was produced whereas on repeating the experiment with two similar straight spur gears, filamentation and breaks in the yarn were soon observed and after running for 60 hours noticeable wearing away of the gears had taken place.

We claim:

1. Crimping gears comprising two gears in meshing engagement for the imparting of rotary motion by one or more of said gears which is driven and for the imposing of crimp to a material running therebetween in which one of the said gears is an integral stepped structure having gear teeth on a portion of greater diameter and gear teeth on a portion of lesser diameter, the other gear being a straight spur gear meshing with the teeth on both portions of said one gear.

2. Apparatus for crimping a filament comprising an integral stepped gear having gear teeth on a portion of greater diameter and gear teeth on a portion of lesser diameter, and a straight spur gear having teeth in engagement with the teeth on the portion of greater diameter of the stepped gear to permit one of the gears to be driven by the other gear, and the straight spur gear teeth being in non-engaging meshing relationship with the teeth on the portion of lesser diameter of the stepped gear so as to be capable of imparting crimp to a filament. 

1. Crimping gears comprising two gears in meshing engagement for the imparting of rotary motion by one or more of said gears which is driven and for the imposing of crimp to a material running therebetween in which one of the said gears is an integral stepped structure having gear teeth on a portion of greater diameter and gear teeth on a portion of lesser diameter, the other gear being a straight spur gear meshing with the teeth on both portions of said one gear.
 2. Apparatus for crimping a filament comprising an integral stepped gear having gear teeth on a portion of greater diameter and gear teeth on a portion of lesser diameter, and a straight spur gear having teeth in engagement with the teeth on the portion of greater diameter of the stepped gear to permit one of the gears to be driven by the other gear, and the straight spur gear teeth being in non-engaging meshing relationship with the teeth on the portion of lesser diameter of the stepped gear so as to be capable of imparting crimp to a filament. 